Just to check my math... if .87kg = 1 liter of biodiesl.

Then 100g = 115ml of biodiesel. Correct?

I was given a much easier version by GCG, get a quart mason jar, add 100ml of 99% ISO, then add eight or nine drops of whatchacallit blue solution, mix thoroughly, then add 10ml of the bio to be checked, then take at least 5ml of your .01N hcl solution and put 5ml in a syringe. take the syringe and add a drop at a time until you get a good bright yellow color change, take the number of ml used and multiply buy 304, this will give you your PPM.

sweet. Thanks fabricator.

I forgot to add, when you add the bio to the ISO indicator mix if the mix stays blue or gets even bluer that will tell you you have a fair amount of soap right off, but if the mixture turns lighter blue to almost a greenish blue you will have a small amount of soap, I have found this to be the case when under 500ppm.

Here's a video of GCG doing the soap test fabricator was talking about....
http://www.youtube.com/watch?v=sJ7ZCyWUTyw&fmt=18

-Graydon